1. Field of the Invention
The present invention is in the field of tools, and more specifically relates a cutter for repeatedly cutting out pieces having identical shape from a sheet of a semi-brittle and semi-rigid material, such as resin-backed grinding disks.
2. The Prior Art
The present invention enables a worker to purchase a large, standard-size resin-backed grinding disk and to cut from it several smaller size grinding disks. The smaller disks are more convenient for detail work. The large standard-size disk is circular in shape and includes a center mounting hole. The smaller disks produced by the cutter must also have a center mounting hole, and, depending on the shape of the jaws of the cutter, the smaller disks can be either circular or polygonal.
The extensive prior art in the field of cutters includes cutters for almost everything from doughnuts to paper. However, the cutting of resin-backed grinding disks has thus far proven to be difficult to accomplish. Such disks are extraordinarily tough and nearly rigid. Further, one side of the grinding disk is practically covered with large particles of grit, which is very securely bonded to the disk. Because of the presence of the grit and a tendency for the resin to fracture in a brittle manner, it has been difficult to obtain a clean edge on the pieces cut from such material. The present invention provides a satisfactory solution to the problem of cutting such grinding disks.
Although the cutter of the present invention is novel combination of structural components, some of the components are old in the art.
For example, in U.S. Pat. No. 2,227,575 issued Jan. 7, 1941 to Eliel, et al., there is shown an adjustable center post for use in selectively positioning the sheet of material to be cut with respect to the cutting edges.
Also, in U.S. Pat. No. 2,598,042 issued May 27, 1952 to Dritz, there is shown a hole cutter that is mounted on a resilient U-shaped member.
U.S. Pat. No. 2,185,005 issued Dec. 26, 1939 to Wagner shows a perforator that is made of sheet metal and is used on paper.
As will be seen below, the cutter of the present invention includes structural features that distinguish it from the cutters of the prior art and that uniquely enable it to accomplish the desired cutting on a very difficult material.